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Acoustic Materials - Noise Control - Lab Manual, Study notes of Noise Control

Some of topics included in this course are: Fundamentals of Acoustics, Levels and Decibels, Divergence and Directivity, Hearing, Human Response to Noise, Frequency Analysis, Sound Sources and Fields, Room Acoustics, Sound Power, Noise Barriers, Outdoor Sound Propagation, Helmholtz Resonator and Vibration Control. Key points of this lab manual are: Acoustic Materials, Nc Rating of Rooms, Acoustic Materials and Nc Rating of Rooms, Coefficients of Porous Materials, Room Noise Criteria, Reporting Re

Typology: Study notes

2012/2013

Uploaded on 10/02/2013

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ME458 Lab 4 8/17/2000 page 1
ME458 Noise Control
Laboratory Exercise #4
Acoustic Materials and NC Rating of Rooms
Objectives:
1) Measure the sound absorption coefficients of porous materials using a standing
wave tube (Impedance Tube)
2) Determine the NC rating of several spaces and compare to recommended values
Part 1: Acoustic Materials
Using the B&K impedance tube, determine the normal incidence absorption coefficient,
statistical absorption coefficient and the impedance for 2 different materials. Compare
your results to published values of absorption coefficients.
Material:
Freq Hz Lpmax Lpmin D
1 D
2 αn Z/ρc αstat Published
value of α
125
250
500
1000
2000
Material:
Freq Hz Lpmax Lpmin D
1 D
2 αn Z/ρc αstat Published
value of α
125
250
500
1000
2000
List of Formulas Used:
αn=
Z/ρc=
αstat=
pf3

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ME458 Noise Control

Laboratory Exercise

Acoustic Materials and NC Rating of Rooms

Objectives:

1) Measure the sound absorption coefficients of porous materials using a standing

wave tube (Impedance Tube)

2) Determine the NC rating of several spaces and compare to recommended values

Part 1: Acoustic Materials

Using the B&K impedance tube, determine the normal incidence absorption coefficient,

statistical absorption coefficient and the impedance for 2 different materials. Compare

your results to published values of absorption coefficients.

Material: Freq Hz Lp (^) max Lp (^) min D 1 D 2 αn Z/ρc αstat Published value of α 125 250 500 1000 2000

Material: Freq Hz Lp (^) max Lp (^) min D 1 D 2 αn Z/ρc αstat Published value of α 125 250 500 1000 2000

List of Formulas Used:

αn=

Z/ρc=

αstat=

Part 2: Room Noise Criteria

Objectives: Measure the background level (in full octave bands) in at least three

different classrooms, offices, or concert halls around campus. From this data, calculate

the NC rating of each space and compare to the recommended values for these spaces.

Center Freq (Hz) A B C 32 64 125 250 500 1000 2000 4000 8000 overall NC rating Recommended NC rating (ASHRAE)

Description of rooms:

A

B

C

Reporting Requirements: Submit a brief, concise lab report. Include : Instrumentation

details, data tables, graphs of NC contours, comments